Medicinal Plant Research 2024, Vol.14, No.4, 223-233 http://hortherbpublisher.com/index.php/mpr 224 these valuable compounds. This knowledge can lead to improved yields of bioactive metabolites, thereby enhancing the medicinal and commercial value of G. lucidum. By elucidating how different stress factors influence the production and accumulation of key bioactive compounds, this study aims to provide insights that can be applied to optimize the cultivation and processing of G. lucidumfor enhanced medicinal efficacy. The scope of the research includes a comprehensive analysis of the molecular and biochemical responses of G. lucidumto environmental stress, with a focus on identifying key regulatory genes and pathways involved in secondary metabolite biosynthesis. This research will contribute to the broader understanding of fungal secondary metabolism and its applications in biotechnology and medicine. 2 Secondary Metabolites inGanoderma lucidum 2.1 Classification and key types of secondary metabolites Ganoderma lucidum, commonly known as Lingzhi or Reishi, is renowned for its diverse array of secondary metabolites, which are primarily classified into triterpenoids, polysaccharides, and other bioactive compounds. Triterpenoids, such as ganoderic acids, are a significant class of compounds known for their pharmacological properties, including anti-inflammatory and anticancer activities (Cao et al., 2017; Čižmáriková, 2017). Polysaccharides, particularly Ganoderma lucidumpolysaccharides (GLPs), are another major group, recognized for their immunomodulatory, antioxidant, and antitumor effects (Lu et al., 2020). Other secondary metabolites include sterols, alkaloids, and phenols, which contribute to the overall therapeutic potential of G. lucidum (Wachtel-galor et al., 2011). 2.2 Biosynthetic pathways of major metabolites The biosynthesis of triterpenoids and polysaccharides in G. lucidum involves complex metabolic pathways. Triterpenoids, such as ganoderic acids, are synthesized through the mevalonate pathway. Key enzymes in this pathway include squalene synthase (sqs), lanosterol synthase (osc), and hydroxy-3-methylglutaryl-coenzyme A reductase (hmgr). The expression of these genes can be significantly upregulated by environmental factors, such as the application of salicylic acid, which enhances ganoderic acid accumulation (Cao et al., 2017; Ren et al., 2019). Polysaccharides are synthesized through a series of glycosylation reactions, where glucose units are polymerized to form complex carbohydrate structures. The molecular mechanisms underlying the biosynthesis of GLPs involve various enzymes that regulate the polymerization and branching of glucose units, contributing to their diverse biological activities (Lu et al., 2020). 2.3 Role of these metabolites in therapeutic applications The secondary metabolites of G. lucidum play crucial roles in various therapeutic applications. Triterpenoids, particularly ganoderic acids, exhibit potent anticancer properties by inhibiting cancer cell proliferation and inducing apoptosis. They also possess anti-inflammatory and hepatoprotective effects, making them valuable in the treatment of liver diseases and inflammatory conditions (Čižmáriková, 2017; Zhang, 2017). Polysaccharides from G. lucidum are well-known for their immunomodulatory effects, enhancing the body's immune response against infections and tumors. They also exhibit antioxidant properties, protecting cells from oxidative stress, and have been shown to improve cardiovascular health by lowering cholesterol levels (Wachtel-galor et al., 2004; Lu et al., 2020). 3 Environmental Stress and Its Impact onGanoderma lucidum 3.1 Types of environmental stress Ganoderma lucidum, a medicinal mushroom known for its bioactive secondary metabolites, is subject to various types of environmental stress that can significantly impact its growth and metabolite production. The primary types of environmental stress include:
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